validate method

@override Object? validate()

Validates the instance. Returns the invalid Object or null when valid.

Implementation

@override
Object? validate() {
  var valid = super.validate();
  if (valid != null) return valid;

  if (_children.isNotEmpty) {
    var invalidChild =
        _children.map((e) => e.validate()).firstWhereOrNull((e) => e != null);

    if (invalidChild != null) {
      return invalidChild;
    }
  }

  return null;
}